The present invention relates to a bidirectional semiconductor component having two symmetrical MOS transistor structures in an antiserial configuration, integrated laterally into a substrate, their drain terminals interconnected.
Bidirectional semiconductor components of the generic type are described in S. Xu et al. in xe2x80x9cBidirectional LIGBT on SOI substrate with high frequency and high temperature capabilityxe2x80x9d IEEE, 2/97. Due to the completely symmetrical design described there in combination with the antiserial configuration of the MOS transistors, the known bidirectional semiconductor component is suitable for use as a matrix switch in telecommunications systems or the like. Asymmetrical applications, such as those in automotive ignition system control circuits, cannot be implemented by the known bidirectional semiconductor components because the required blocking ability of approx. 400 V can be achieved only asymmetrically at the present time.
The bidirectional semiconductor component according to the present invention offers the advantage over the related art that it is possible to implement blocking voltages of different levels. An asymmetrical blocking ability may be achieved with a simultaneous guarantee of a low resistance at powerup due to the fact that a zone having the same type of conductivity as the drain region, however, having a higher doping than the drain region, is located upstream from a pn junction of one of the MOS transistors in a junction area with the drain region.
Due to the advantages achievable with the design of the bidirectional semiconductor component according to the present invention, it is especially suitable for use as a short-circuit switch for short circuiting a primary winding of an ignition coil in an ignition system of a motor vehicle. It is known that with an ionic current ignition, the primary winding of the ignition coil is to be short-circuited by the secondary winding of the ignition coil after the ignition pulse has been triggered on a sparkplug because extinction of the spark is defined by this short-circuiting. In this use as provided according to the present invention, the bidirectional semiconductor component used as a short-circuit switch receives blocking voltages of different levels, namely the battery voltage on the one hand and the terminal voltage of a transistor stage connected as a Darlington, for example, on the other hand. According to the buffering of the pn junction of the one MOS transistor provided with the bidirectional semiconductor component according to the present invention, it is possible to achieve an asymmetrical blocking ability of the semiconductor component by way of which the different blocking voltages can be compensated for.